14 Butomaceae, Hydrocharitaceae 



Flowers diclinous. Fruit strongly compressed. 



Sagittaria. 



Suborder 3. BuTOiMlNEAE. Flowers hypogynous 

 or epigynous, mostly heterochlamydeous. Ovules scat- 

 tered over inner surface of carpel on branching placentae. 



Fam. 6. BUTOMACEAE. Marsh plants with cov.- 

 s'^XQMOws, flowers. Infloj'esceiice cymose, often umbel-like. 

 Flowers monoecious, usually markedly heterochlamy- 

 deous, 3-merous. K 3, C 3, A 6 (3 pairs) + 3-00 , in the 

 last case the outer ones sterile. G 6-00 often united 

 at the base with cxd ovules scattered over their inner 

 surfaces. Fruit of follicles. 



Only British genus (perianth homochlamydeous, 

 persistent) : Butomus. 



Fam. 7. Hydrocharitaceae. Submerged or 

 floating water plants. Leaves mostly spiral, sometimes 

 cyclic or distichous. Flowers solitary or cymose, at 

 first enclosed in an envelope of 1-2 bracts, usually 

 diclinous, mostly heterochlamydeous, 3-merous. K 3, 

 C 3, A 3 +(3 -1- 3 -1- 3 + 3), the inner and outer stamens 

 sometimes staminodal. 0(2-15). Placefitae parietal, 

 bearing o) orthotropous to anatropous ovules with 

 2 integuments. Stigma often deeply bifid. Fniit 

 mostly dehiscing irregularly with 00 seeds. 



a. Carpels 6-1 S' P/(^^^;z/'«^ projecting far inwards. 



Subfamily i. Stratiotoideae, Fresh water plants. 

 Foliage leaves spiral. 



Tribe i. Stratioteae. Leaves partly submerged. 

 % flowers sessile in the 2-leaved spathe. 



Leaves erect narrow serrate. Stratiotes. 



